One issue that came up in the arguments yesterday was the role of the filibuster in increasing legislative inertia. Current cloture practice, which is totally inconsistent with how the Senate operated for most of our history, complicates the Court's consideration of the Affordable Care Act case and is pushing the Justices toward a more radical opinion. How so?

1. It undermines the argument that political remedies can protect federalism.

Nobody thinks that Republicans can get sixty seats in the Senate. As a result (unless you come up with a very creative view of the reconciliation process), the Affordable Care Act functionally cannot be repealed by Congress. Without the filibuster, the argument for judicial deference would be more persuasive for those Justices who are concerned about the individual mandate.

2. It makes the severability argument more implausible.

The Justices probably do not believe that Congress can quickly replace the individual mandate with another funding mechanism before 60 votes cannot be found for an alternative. Since leaving the rest of the ACA intact without the individual mandate would be a disaster, throwing out the entire Act looks more attractive.

Justice Kennedy suggested that he was more interested in the actual Congress than in the hypothetical Congress, and the chief difference between them is that you need a supermajority to act in the Senate.

I think there's another filibuster-related aspect to this case. Democratic Senators will generally be rather upset if ACA is overturned, if only the grounds of judicial overreach and (as Noah Millman suggested) that fact that it's very hard to legislate if SCOTUS is willing to change the rules after the fact to invalidate the legislation. I suspect that's going to make the confirmation of justices nominated by Republican presidents very, very hard, given that it only takes 40 senators to filibuster such nominations. What are such nominees going to say that will reassure Democrats that they won't engage in the kind of overreach that current justices seem headed for? And I don't think the fact that the Court might not have nine justices as a result of such a filibuster is going to be a deterrent - how is losing 5-3 worse than losing 5-4?

Of course, the inverse could happen as well, with Republicans filibustering any future Obama nomination on sight.

The overturning of ACA will very possibly lead to a slow-motion constitutional crisis; that, I suspect, will be its eventual effect, and not whatever happens in November. The filibuster is one potential "victim" of such a crisis.

You're awfully optimistic about the willingness of D Senators to play hardball. There's no evidence of that at all.

Worse yet, you're making the same mistake that people like Jeff Toobin made about the Court: you're assuming the Right is willing to play by the rules. They aren't. If the Dems were to filibuster a Court nominee or the repeal of the ACA, the Rs would eliminate the filibuster.

You're awfully optimistic about the willingness of D Senators to play hardball. There's no evidence of that at all.

To some extent that depends on how upset they believe their base is with a ruling overturning ACA. But I think the issue of how difficult it would be to legislate in a world where SCOTUS felt free to overturn legislation based on ever-shifting criteria will be a powerful motivator.

If the Dems were to filibuster a Court nominee or the repeal of the ACA, the Rs would eliminate the filibuster.

That was actually my point. And, once gone, it's not coming back. Long-term, the filibuster is far more helpful to Republicans than Democrats, as the past two years has demonstrated.